Free-turbine turbomachine comprising equipment driven by the free turbine

Abstract

A turbomachine including a gas generator endowed with a first shaft, a gear box, at least one reversible electric machine coupled to the gear box, and a free turbine endowed with a second shaft and rotationally driven by a gas stream of the gas generator and at least one accessory coupled to the accessory gear box, wherein the turbomachine includes a first mechanical coupling means configured to mechanically couple said first mechanical shaft to the accessory gear box in a first configuration and to mechanically uncouple said first mechanical shaft from the accessory gear box in a second configuration, and a second mechanical coupling means configured to mechanically couple said second mechanical shaft to the accessory gear box in a first configuration and to mechanically uncouple said second mechanical shaft from the accessory gear box in a second configuration.

The invention claimed is: 
     
       1. A turbomachine including a gas generator comprising a first mechanical shaft, an accessory gear box, at least one reversible electric machine coupled to the accessory gear box, a free turbine provided with a second mechanical shaft and rotationally driven by a stream of gas generated by the gas generator, and at least one accessory coupled to the accessory gear box,
 wherein the turbomachine further comprises a first mechanical coupling means configured to mechanically couple said first mechanical shaft to the accessory gear box in a first configuration of the first mechanical coupling means and to mechanically uncouple said first mechanical shaft from the accessory gear box in a second configuration of the first mechanical coupling means, and a second mechanical coupling means configured to mechanically couple said second mechanical shaft to the accessory gear box in a first configuration of the second mechanical coupling means and to mechanically uncouple said second mechanical shaft from the accessory gear box in a second configuration of the second mechanical coupling means, the electric machine being dimensioned to drive the gas generator and said at least one accessory during the start-up of the turbomachine. 
 
     
     
       2. The turbomachine as claimed in  claim 1 , further comprising a control unit of said at least one electric machine, the control unit being configured to put the electric machine in motor mode during the start-up of the turbomachine, and to put the electric machine in generator mode when the second coupling means is put in its first configuration. 
     
     
       3. The turbomachine as claimed in  claim 2 , wherein the second mechanical coupling means is put in its second configuration from the start-up phase of the turbomachine until a parameter of the second mechanical shaft or of the second mechanical coupling means has exceeded a power threshold above which the free turbine is in a power configuration allowing it to drive said at least one accessory without the assistance of the electric machine. 
     
     
       4. The turbomachine as claimed in  claim 1 , wherein the first mechanical coupling means comprises a first free wheel and the second mechanical coupling means comprises a second free wheel. 
     
     
       5. The turbomachine as claimed in  claim 1 , wherein the first mechanical coupling means and the second mechanical coupling means are contained in a casing of the accessory gear box. 
     
     
       6. The turbomachine as claimed in  claim 1 , further comprising an additional accessory gear box connected to the first mechanical shaft to constantly couple additional accessories directly to the gas generator. 
     
     
       7. An aircraft with rotary wings comprising at least one turbomachine as claimed in  claim 1 , a main gear box and a mechanical coupling between the free turbine and said main gear box.